Thanks in advance for any ideas the group may have. I am dealing with gurgling in a hot water stand pipe for baseboard heat. I thought it was air trapped at the top, so I had a bleeder valve installed at the top of the stand pipe this summer. But there's no air in the pipe, yet the issue persists. I have tried flushing the system; it was also flushed by pros when the bleeder was installed a couple months ago. Most interesting to me is that the noise is very cyclical; one big gurgle every 4-5 seconds, like clockwork. It sounds like a wave within a horizontal pipe. Silence in between. I believe the noise may be reverberating up the pipe from the basement. For some reason they left a 1 1/2" pipe for the stand pipe, where it goes down 2 floors to the basement and bends 90° for several feet before reducing back to 3/4". I have lots of theories - would like your opinion. Perhaps the upper cross section of the horizontal larger diameter pipe is filled with air, and the air can't get pushed out through the reducer into the 3/4" pipe. That would create a wave/gurgling sound if the air is sloshing around. Perhaps the sudden increase in diameter is allowing air to form within the vertical standpipe. But I am no expert. Any theories, or how to test? Worst case I drain the system and replace the 1 1/2" standpipe with 3/4" copper but I'd hate to go through that expense on my single theory.

Hello, this week I noticed water filling the bucket under the boiler TP relief valve. I checked the schrader valve on the expansion tank and confirmed that the bladder has failed and it is filled with water. I purchased a replacement tank (Amtrol 30 EXTROL pre-charged to 12 PSIG. 4.4 Gallon Volume). I’ve mapped out my system, read a lot about the job and feel ready to tackle it. This is the procedure I plan on: [list=1] [*]teflon tape threads of new tank (leave top 2 or 3 threads bare) [*]fill tank to 15lbs to match boiler (2 story home, boiler in basement) [*]turn off boiler, allow to cool to 100 degrees F [*]turn off all 4 valves on boiler system [*]drain boiler to 0 psi from drain on bottom right using washing machine hose & 5 gal bucket [*]close drain [*]unscrew old tank using wrench on the top fitting (I understand it will be very very heavy and may try to drain it first) [*]screw new tank into place [*]open water feed valve slowly and pressurize boiler to 15# [*]open the remaining 3 valves, turn on boiler power & set the thermostat to call for heat [/list] I have a few questions before I replace the expansion tank on my boiler. [list=1] [*]Is it necessary to shut off all boiler system valves or just the water supply valve? If it is all, is there a specific order to shutting them off? [*]The water supply valve is the one on the left, above the back flow preventer? [*]Will I get air in the system with this replacement? If yes, how to purge it? [/list] Thank you for any advice or comments.